docs(pages): Zola is preinstalled in v2/v3 build image

ZOLA_VERSION is now optional — Zola is preinstalled in the Pages v2/v3
build environment so builds work without any env var configuration.
Users can still pin a specific version via ZOLA_VERSION if needed.

Author: ericclemmons

src/content/docs/pages/framework-guides/deploy-a-zola-site.mdx

@@ -81,11 +81,11 @@ Upon running `zola init`, you will prompted with three questions:
 
 <PagesBuildPreset framework="zola" />
 
-Below the configuration, make sure to set the **Environment Variables (advanced)** for specifying the `ZOLA_VERSION`.
+Zola is preinstalled in the Cloudflare Pages build environment, so no additional configuration is required. You can optionally set the `ZOLA_VERSION` environment variable under **Environment Variables (advanced)** to pin a specific version.
 
-For example, `ZOLA_VERSION`: `0.17.2`.
+For example, `ZOLA_VERSION`: `0.19.2`.
 
-After configuring your site, you can begin your first deploy. You should see Cloudflare Pages installing `zola`, your project dependencies, and building your site, before deploying it.
+After configuring your site, you can begin your first deploy. You should see Cloudflare Pages building your site with Zola, before deploying it.
 
 :::note